Propulsion of aircraft



sept, 29,1925'.

y Y 1,555,422 C. LORENZEN PROPULSION OF AIRCRAFT Filed Aug. 1s.l 192s 12ga I Rg! A Patented Sept. 29, 1925.

UNITED STATES CHRISTIAN LORENZEN", O'F`BERLIN-NEUKOLLN, GERMANY.

PROPULSION OF AIRCRAFT.

Application led August 16, 1923. Serial No. 657,807.

'/'o all whomy it may concern.'

lle it known that I, CHRISTIAN LonENzEN, a citizen of the German Republic, residing at llerlin-Neukolln, Germany, have invented 5 certain new and useful Improvements in the lropnlsion of Aircraft, of which the following is a specification.

'lhe means of propulsion for aircraft- Inotor and propeller-are calculated for a normal density of air (l atm.), at which the highest efficiency is attained. W ith the decrease of density atv increased heights the Inotor and propeller lose correspondingly in eliiciency, and consequently the machine does not attain the speed whichv she otherwise Inight do in the case of decreased density ofairin view of the decrease in air resistance.

For overcoming this drawback motors have already been employed on the one hand whose etliciency remains constant with all densities of air, for example motors which are furnished with a compressor plant operated by 'any exhaust gas turbine and connected with the intakeof the motor, which brings the vmore orl less densified outer air fed to the motor to v.normal atmospheric pressure. Onthe other ha'nd'propellers with variable pitch have been em- 30 ployed, whereby `the inclination'V of the blades is capable of adjustment in accordance with the variation of air density. Both the Inotor and the propeller-"then require,

however, the continual observation. of the.

pilot who, with the reate'stl .amount of attention, will not find 1t possible to effect the control of same with such regularity that in the constantly varying air density a constant efliciency of the motor is attained and a corresponding pitch given to the propeller. There are, therefore, always differences in the turning moment ofy motorl and propeller.

The present invention consists in regulat-l ing by automatic organs the constant efficiency ot' the Inotor and the Variable pitch ofthe propeller in uniformity With one another, the operation of these organs being effected' by the factor 'governing the eflieienc'y of the propeller and motor, 4namely the density of the air prevailing at the time, which thereby represents the combinatory element between motor and propeller.

For this purpose the motor and propeller, orv'the control valve in the intake of the motor and-the adjustmentp'rod forv the pro-` peller blades respectively, Aare made dependent upon Inembranous organs reacting lupon the an' density, which are arranged in such a Inanner that the eieieney of the motor re regulated in continual agreement by the.

air itself that theeffi'ciency always remains constant, whereby the aircraft is able to fully employ the advantage of decreased density of air With regard to its Speed.

A'lhe invention more particularly consists in arranging the membranous organs operating the adjustment rod for the ropeller blades and the regulation valve in t e intake of the motor in such'a man-ner that their reaction upon theV alteration in air density can be varied in agreement. In this manner itis possible, naturally with corresponding constructionof the motor and propeller, for increasing the efliciency of the motor to induct to the same a mixture of over l atm.- and to adjust the pitch of the propeller accord- Ingly. The constancy of this high efficiency of the motor and the corresponding regulation of the pitch of the propeller is then effected automatically and in agreement as previously described.

I In the drawigf- Figs. 1-3 illustrate the membranous organs operating the adjustment device for the propeller blades; l

Flg. 4 shows in plan and section the membranous operating organ for the regulating valve in the intake of the motor;

Fig. 5 shows the complete arran ement of I the propulsory means for aircra t according 4to the invention.

The membranous operati-ng organ of the adjustment device` for the'propeller blades consists of a container in which is imprisoned an amount of air of the density prevailing at sea level. The cover of the conltainer is formedas a membrane or a piston or secured to a resilient tubein such a manner that it has a certain possibility of move-- Inent. This container rotates inconjunction with the propeller, and the vmovement of the cover operates through suitable means upon the adjustment device.

1, 1 is the axis of rotation of the ropeller shaftv 2, The vertically stan 'ng blades 3, 3 rotate in bearings 4, 4. The ad csf justment rod 5, 5 engages at the points 6, 6 of the blades. The rods 5 are secured to aplate 7, which represents the cover of the container 8 with t e imprisoned air. Between the cover 7 and the cylindrical wall 9 of the container 8 is connected a-resilient membrane 10, which consists of an undulated sheet of metal or other suitable resilient organ. y

. In the container 8 the pressure is 1 atm., obtained for example by connecting the container with the outer air when the machine is at sea level and then permanently closing same. If the outer pressure decreases by the fact that the machine has attained a higher altitude the air imprisoned .in the container 8 forces the cover outwardly until it has reached an extent where all the forces working upon the cover 7 are counterbalanced. This movement draws upon the rods 5, and the blades are rotated round the point 4 in such a manner that the pitch is increased. If the outer pressure again decreases by the descent of the machine an alteration in the pitch of the blades is again effected by the retraction of the cover 7, etc. The wholedevice is provided for protection with the hood 11.

As it is the air pressure itself which regu- `lates the pitch of the propeller, the latter,

if the amount of imprisoned air is correctly calculated, must always be capable of producing a uniform turning movement at all densities, so that the eiiiciency corresponds to the constant eiliciency of the motor.` In this manner the pilot is no longer burdened with the adjustment of the propeller.

The membranous organ for operating the regulating valve in the intake of the motor is illustrated in Fig. 4. 12, 12 is the valve, which opens and closes the openings 13, 13 for the air proceeding to the intake 14 of the motor from the compressor plant. The assage of the air from the compressor p ant to the intake 14 is shown by an arrow. The

valve plates'12, 12 are located upon a valve rod 15 the one end of which is attached to a membranous container 16. Thiscontainer 16 is lled with air at 1 atm. pressure and closed from the outside.' `It is located in a container 17, which is connected with the intake of the motor, so that the same pressure prevails therein as in the intake. The container 16 is sus ended in suitable manner in the container 1 for example on to the cover 18, the container 17 being moreover closed from the outside. If the pressure in the intake and consequently in the container 17 decreases, the air in the membranous organ 16 expands and thev valve 12, I12 is opened, so that the air from the compressor can enter the intake. When the pressure here has correspondingly increased the container l? Wll again be retracted and the valve is c ose In the case of flying machines which are only intended to attain moderate heights of 20000-26000 feet it is sufficient to employ a device as illustrated in Fig. 4. The membranous organ 16 is thereby mounted in a container 17 closed from the outside, and the intake 14 runs directly into the intake system' of the motor. For machines which are to y at greater altitudes of 30000-50000 feet the container in which the membranous organ is mounted is preferably sufficiently' .large for simultaneous reception of the whole motor and all passengers upon the machine. The intake 14 is then, as illustrated in Fig. 3, open towards the space 24 formed by the body of the machine and closed up from the outside. The motor draws in air from this space. Naturally, the container 17 serving for reception of the membranous container 16 is likewise open towards the s ace 24.

. I the regu ating valve, as described above, is adjusted for a normal air density, i. e., for 1 atm., the air proceeding from the compessor and having a higher pressure will converted into a uniform pressure for the motor of 1 atm., and the motor operates with a constant eiiiciency in agreement with the above-described corresponding adjustment of the pro ller pitch.

It has been s own that by the em loyment of a discharge gas turbine an the compression of the air. eected in stages the air cannot onl fbe brought to atmospheric pressure at t e greatest heights available for travelling, which are between 50000 and 56000 feet, but also greatly beyond this. The compressor even in these heights delivers air at a higher pressure than 1 atm. The invention makes use of this fact in the manner that a suitable adjustment device 25 is mounted upon the membranous organ 16 operating the regulating valve, which device, for example y adjustment of the point of suspension of the container 16 in -he container 17, permits variation in the reaction of the membrane 16 upon the density of the air in the intake. The adjustment device, which merely needs to consist of a simple adjuster, permits the adjustment of the regulating valve in such a manner that, for exam le, it already opens when the pressure in t e intake falls below 11/2 atm. In this manner the pilot, by regulation of the reaction of the membrane 16 upon the density of air, can obtain as high a pressure as desired in the intake withln the limits of the capabilities of the compressor. Naturally, for this a corresponding construction of the motor is necessary in such a manner that same is capable of employinga mixture of over 1 atm. If such a device is provided upon the membranous organ for the operation of the regulating valve the space in the flying machine is referably divided into two compartments y the wall 26, of which, the compartment 24 is employed for mounting the motor with its accessories, fuel, etc., whilst the rear space 27, which is only filled with air of 1 atm. for which a second similar regulating valve 28 is employed, serves for reception of the passengers. l

If, in this manner, the efficienc of the motor is -fvaried by regulation, the pilot must also be able to correspondingly adjust the propeller. For this purpose the Vhollow sp'ace of the container 8 which is located on the propeller hub is, for example, connected to a labyrinth packing 29 and a pie conduit 30 extending to the pilots seat. y the pilots seat is located a small air pump 31. By manipulation of the latter the pilot is able to vary the -amount of air under# neath the piston according to choice, and hereby bring the pitch of the propellerV into accordance with the particular turning moment of the motor.

1. The combination with aero: lanev propulsion means including a prope ler and a driving motor having an air intake of means functioning automatically to effect simultaneous regulation of the air intake and the pitch of the propeller blades to comconstant eiiciency irrespective ofthe density of the surrounding atmosphere, said means comprising sealed containers each imprisoning air at a deiinite rassure, said containers being capable o contraction and expansionand being exposed externally to the pressure of the surrounding atmosphere, and means responsive to expansion and contraction of said containers for regulating the intake of the motor and simultaneously varying the pitch of the propeller blades.

2. The combination with an aero-plane motor having an air intake of means functioning to automatically regulate said intake in such manner as to maintain the motor at constant eiiciency irrespective of variations of density of the surrounding air, said means comprising an outer casing open r`to the atmosphere, a sealed inner container imprisoning air at a different pressure and exposed externally to Jthe atmospheric pressure of the outer container, said inner container being capable of expansion and contraction in response to variations of the atmospheric pressure, valve means operating in said air intake and a connection between said valve means and said container whereby opening and closing of the valve means is controlled by expansion and contraction of the container.

3. The combination with the structure of claim 2 of means for regulating expansion and contraction of sai container in re-` sponse to the variation of the atmospherlc pressure.

In testimony whereof I have aixed my signature.

CHRISTIAN LORENZEN.` 

